Police are urging people to be vigilant after callous criminals targeted two residents in their 90s in Hertfordshire.

A spokesman for Herts Police said: “We are urging people to remain vigilant around unexpected callers.

“On both occasions a man knocked at the door and claimed he was there to deal with a problem with the victims’ water supply.

“He then instructed the victims to repeatedly turn their kitchen taps on and off.

“While they were doing so, the man searched the properties and stole cash.”

Both victims were aged in their 90s.

The suspect is described as a white man, aged between 25 and 40 years old, of slim build and wearing a hat.

Detective Sergeant Jon Leak, from the Constabulary’s Operation Manhunt unit, said: “Bogus callers are very persuasive and plausible and we are calling upon residents, their families, friends and carers to be aware of these callers and take precautions against them.

“If you haven’t already pre-arranged an appointment, our advice would be not to open the door to anyone.

“If you are expecting someone, it’s a good idea to agree a password which can be given on arrival, to help verify if a caller is genuine.

“Always ask for identification and if you have any doubts, contact the company in question to be sure a caller is who they say they are before you let them in.

“Although distraction burglaries account for a small proportion of burglaries in Hertfordshire, we want to remind people of the importance of only allowing people in when they are entirely convinced that they are who they say they are.